Hi TR88,
First, please open the cover to your printer.
From left to right, are the following ink tanks installed:
CLI-251 BK (Black)
CLI-251 G (Gray)
CLI-251 Y (Yellow)
PGI-250 PGBK (Black)
CLI-251 C (Cyan)
CLI-251 M (Magenta)
Please make sure none of them are "photo" ink tanks, like PM or PC. that would cause this color shift.
Next, let's do another test of your PIXMA iP8720.
Please load a sheet of letter sized (8.5" x 11") plain paper in the printer.
Once loaded, please hold down the Resume button until the Power light blinks 2 times, then let it go.
The Resume button is the middle button.
Does your printout look like the example below?
